while 문 스크립트좀 가르쳐 주세요

#! /bin/sh
# File : acq1.sh
# Set message on
set -x

# Assign values to variables
num=1
nangle=100 fangle=-35 langle=-10
nt=750 dr=0.004

# Name input model file
inmodel=model${num}

# Name output seismic file
outseis=seis${num}.su

#================================================
# Create the Seismic trace wirh "triseis"
# i-loop = 81 source positions
# j-loop = 21 hydrophone position (split-spread) per shot position
# k-loop = layer 2 through 5 (do not shoot layer 1 and 6)

echo " *** Begin loop over triseis. *** "

i=0
while [ "$i" -ne "81" ]
do

fs=`bc -l << -END
$i * 0.05
END`
sx=`bc -l << -END
$i * 50
END`
fldr=`bc -l << -END
$i + 1
END`

j=0
while [ "$j" -ne "21" ]
do
fg=`bc -l << -END
$i * 0.05 + $j * 0.05
END`
gx=`bc -l << -END
$i *50 + $j *50 - 1400
END`
offset=`bc -l << -END
$j * 50 -1400
END`
tracl=`bc -l << -END
$i * 21 +$j + 1
END`
tracf=`bc -l << -END
$j + 1
END`

echo "Sx=$sx Gx=$gx fldr=$fldr Offset=$offset tracl=$tracl fs=$fs fg=$fg"

k=2
while [ "$k" -ne "6" ]
do

triseis < $inmodel xs=2,6 xg=0.6,5.6 zs=0,0 zg=0,0 nangle=$nangle fangle=$fangle langle=$langle \
kreflect=$k krecord=1 fpeak=12 lscale=0.5 ns=1 fs=$fs ng=1 fg=$fg nt=$nt dt=$dt |
suaddhead nt=$nt |
sushw key=dt,tracl,tracr,fldr,tracf,trid,offset,sx,gx a=4000,$tracl,$tracl,$fldr,$tracf,1,$offset,$sx,$gx >>temp$k

k=`expr $k + 1`

done
j=`expr $j +1`

done
i=`expr $i +1`

done

echo " +++ End looping over triseis. +++"

#================================================

# Sum contents of the "temp" file
echo " +++ Sum file +++"
susum temp2 temp3 > tempa
susum tempa temp4 > tempb
susum tempb temp5 > $outseis

# Remove temp files
echo " --- Remove temp file.---"
rm -f temp*

# Exit politely from shell script
echo " ### Finished!!! ###"
exit

i=0 부터 시작하는 while 문 스크립트가 돌아야 되는데 에러 메세지만 나오고 돌지를 않아요...ㅜ